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Biomedical subjects

G C Cole

Publications and source records attributed to G C Cole.

11 recordsLinked to original sources
PubMed2005

Rotational spectrum, inversion, and geometry of 2,5-dihydrofuran...ethyne and a generalization about Z...H-C hydrogen bonds.

The ground-state rotational spectra of nine isotopomers of a complex formed between 2,5-dihydrofuran and ethyne were recorded with a pulsed-jet, Fourier-transform microwave spectrometer. Rotational and centrifugal distortion constants were obtained for C4H6O...HCCH, C4H6O...DCCH, C4H6O...HCCD, C4H6O...DCCD, [3,4-D2]-C4H6O...HCCH, C4H6O...H13CCH, C4H6O...HC13CH, , and [3(13C]-C4H6O...HCCH. The substituted species were studied in their natural abundances. For the more abundant isotopomers, weak c-type transitions as well as strong a-type transitions were observed. The primary intermolecular binding was shown to consist of a hydrogen bond formed by the ethyne subunit acting as the proton donor and the O atom of 2,5-dihydrofuran as the proton acceptor. The complex has a plane of symmetry that includes the O atom and the ethyne subunit, with a pyramidal configuration at oxygen. A fit of the principal moments of inertia of all nine isotopomers under the assumption of unperturbed 2,5-dihydrofuran and ethyne geometries yielded the values r(O...H)=2.127(8) A, phi=57.8(18) degrees , and theta=16.2(32) degrees, where phi is the angle made by the HCCH subunit at O and theta is the angular deviation of the O...H-C nuclei from collinearity. This geometry is compared with those obtained by ab initio calculations conducted with a range of basis sets and with electron correlation taken into account at the MP2 (Møller-Plesset second order) level of theory. A small inversion doubling (approximately equal to 20-30 kHz) of c-type transitions, well resolved only for the parent isotopomer and [3HCCH, was attributed to a vibrational motion that inverts the configuration at oxygen. A one-dimensional model for this motion was used with a double minimum potential energy function of the type V(phi)=alphaphi(4)+betaphi(2) to estimate the observed separation DeltaE(01) of the lowest pair (v=0 and v=1) of associated energy levels. The predicted DeltaE(01) had the same magnitude as that deduced from the inversion doubling of the c-type transitions. The geometry of C4H6O...HCCH is compared with those other B...HCCH, where B is vinyl fluoride, oxirane, and thiirane. A rationalization of the angular geometries of various B...HX, where X=F, Cl, Br, or CCH, is presented.

Journal Article↗
PubMed2004

The nature of the complex formed between pyridine and hydrogen bromide in the gas phase: an experimental approach using rotational spectroscopy.

The rotational spectra of two isotopomers, C(5)H(5)N...H(79)Br and C(5)H(5)N...H(81)Br, of a complex formed by pyridine and hydrogen bromide were observed by using a pulsed-jet, Fourier-transform microwave spectrometer that incorporated a mixing nozzle. Rotational constants, centrifugal distortion constants, and nuclear quadrupole coupling constants for the (14)N and Br nuclei were determined. The rotational constants indicate that the observed complex has a planar geometry of C(2v) symmetry, with the HBr subunit lying along the C(2) axis of pyridine. These conclusions are in good agreement with those obtained earlier from infrared spectroscopy in cryogenic matrices and ab initio calculations. The distance r(N...H)=1.137(2) A was obtained by fitting the rotational constants under the assumption of an unchanged pyridine geometry and with r(H-Br) fixed at the value obtained through an ab initio calculation. The nuclear quadrupole coupling constants were interpreted, with the aid of ab initio calculations for the complex, as well as hydrogen-bonded and ion-pair limiting models for the interaction of pyridine and HBr, to establish that the complex may be visualized in terms of a substantial contribution (>60%) of the ionic structure C(5)H(5)NH(+)...Br(-) to its valence-bond description. The intermolecular force constant k(sigma)=57.8(16) N m(-1) determined from the centrifugal distortion constants Delta(J) of the two isotopomers is also consistent with a strongly bound complex involving partial proton transfer.

Journal Article↗
PubMed1994

Twenty-year survival following excision of primary CNS lymphoma without radiation therapy: case report.

The prognosis of primary central nervous system lymphoma (PCL) is very poor with a mean survival of 3-6 months without treatment and 15-45 months following radiation therapy. PCL is very sensitive to radiation therapy, but recurrence is frequent. A response of the tumour to steroids has also been documented. This report describes a patient who had surgery for a solitary PCL without subsequent radiation therapy or steroid medication and who had no evidence of tumour recurrence 16 years later. He remains well 20 years after surgery. No case of long-term survival following surgery alone for PCL has been reported previously. Surgical excision may have a place in the management of solitary PCL.

Aged↗
PubMed1989

An epidemiological survey of primary tumours of the brain and spinal cord in South East Wales.

This survey is founded on 526 patients who presented with a primary tumour of the brain, spinal cord or their coverings over a seven year period. The patients resided in one of the three counties comprising South East Wales, which has a population of about 1.3 million. Each tumour type is classified according to age, sex and area of residence of the patient. Age and sex adjusted annual incidence rates were calculated for each tumour type. All types of glioma have a higher incidence in males, while meningiomas are twice as common in females. Gliomas are the most commonly occurring tumour with an average annual incidence of 3.6 per 100,000 and a peak incidence for malignant astrocytomas of 7.6 in the 55 to 64 year age group. The low grade astrocytoma is the most common tumour of childhood. Oligodendrogliomas occur most commonly in adults between the ages of 35 and 44 years. In this survey there is an unexplained relatively high incidence of oligodendrogliomas. The majority of primary tumours arose in the brain, but there were 24 tumours of the spinal cord, nerve sheath and meninges. Comment is made on the presence and possible aetiological significance of chemical industries within South East Wales.

Adolescent↗
PubMed1981

Ocular malignant melanoma in South African blacks.

The incidence of primary ocular malignant melanoma in blacks during the last 25 years in a large part of the Transvaal Province of South Africa is reported. Only 8 cases were diagnosed, 1 uveal, 4 conjunctival, and 3 orbital. During this same period 153 cases of primary ocular malignant melanoma were diagnosed in whites. The rarity of these tumours among blacks is stressed and the reasons for this infrequent incidence discussed.

Adult↗
PubMed1979

In vitro propagation of Plasmodium falciparum for merozoite antigens.

A system with continuous flow of medium that uses disposable tissue culture flasks for the in vitro cultivation of P. falciparum is described. This scaled-up modification of the Trager and Jensen method gives merozoite yields sufficient for experimental vaccine studies in animals. A method of increasing the yield of merozoites by decreasing the pH of the medium is presented.

Animals↗
PubMed1975

The instrumentation of a Zanasi LZ/64 capsule filling machine.

The dosator system of a Zanasi LZ/64 capsule filling machine was modified and strain gauges were fitted. These were used to measure the forces on the powder being filled during compaction and ejection. The patterns of those forces produced were shown to differ between different materials and between lubricated and unlubricated materials. Tentative reasons for the observed differences have been suggested.

Capsules↗
PubMed1974

Isolation and characterization of bacteria that grow on methane and organic compounds as sole sources of carbon and energy.

Bacteria capable of growth on methane and a variety of complex organic substrates as sole sources of carbon and energy have been isolated. Conditions used to rigorously establish the purity of the cultures are described. One facultative methylotroph has been studied in detail. This organism has peripherally arranged pairs of intracytoplasmic membranes characteristic of obligate methylotrophs. This isolate apparently utilizes the serine pathway of formaldehyde fixation. The location of methane oxidizers in a dimictic lake indicates that these organisms prefer less than saturating levels of dissolved oxygen. Laboratory experiments confirmed the preference of these organisms for atmospheres containing less oxygen than air.

Anti-Bacterial Agents↗
PubMed1972

Comparison of fluorescent antibody induced by rubella virus in vaccinee and convalescent individuals.

Specific rubella antibody detectable by indirect immunofluorescence developed in response to immunization with attenuated rubella vaccine, HPV-77, DK-12. Fluorescent antibody (FA) was found when vaccinee sera were reacted with antigens synthesized in three different acutely infected continuous cell lines: BHK-21, LLCMK-2, and RK-13. FA titers were high, and they correlated with antibody titers obtained by hemagglutination-inhibition tests. Levels of FA in vaccinated individuals were slightly lower than those found in persons recovered from natural rubella infections. Rubella FA persists a long time in convalescent individuals and appears to be maintained for at least 19 months in vaccinees.

Animals↗